fix #1070 (#1389)

* fix #1070

* test: add more tests

rest/httpx/responses.go

@@ -14,13 +14,17 @@ var (
 )
 
 // Error writes err into w.
-func Error(w http.ResponseWriter, err error) {
+func Error(w http.ResponseWriter, err error, fns ...func(w http.ResponseWriter, err error)) {
 	lock.RLock()
 	handler := errorHandler
 	lock.RUnlock()
 
 	if handler == nil {
-		http.Error(w, err.Error(), http.StatusBadRequest)
+		if len(fns) > 0 {
+			fns[0](w, err)
+		} else {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+		}
 		return
 	}
 

rest/httpx/responses_test.go

@@ -95,6 +95,18 @@ func TestError(t *testing.T) {
 	}
 }
 
+func TestErrorWithHandler(t *testing.T) {
+	w := tracedResponseWriter{
+		headers: make(map[string][]string),
+	}
+	Error(&w, errors.New("foo"), func(w http.ResponseWriter, err error) {
+		http.Error(w, err.Error(), 499)
+	})
+	assert.Equal(t, 499, w.code)
+	assert.True(t, w.hasBody)
+	assert.Equal(t, "foo", strings.TrimSpace(w.builder.String()))
+}
+
 func TestOk(t *testing.T) {
 	w := tracedResponseWriter{
 		headers: make(map[string][]string),